Chronic pain and allergic diseases are two widespread global health challenges lacking clear preventive measures or satisfactory therapeutic solutions. Approximately 30-40% of the world's population suffers from at least one allergic disease while one out of every 10 adults is newly diagnosed with chronic pain each year. Tissue mast cells orchestrate allergic pathologies. An emerging body of evidence also places them as critical mediators of both protective and maladaptive pain. Mast cells have been clinically associated with migraines, inflammatory bowel disease, fibromyalgia, and bladder pain. In both migraine and chronic vulvar pain, a history of allergies is known to increase the ris of developing the pain condition. While the roles of mast cells in allergies and pain have been separately studied, the interaction of these pathways has not been investigated. Here we propose to dissect mast cell regulation of allergy- driven pain via two closely connected specific aims: (1) Characterize contributions of mast cell activation, by different IgE antibody clones against the same antigen, to hind paw thermal and mechanical sensitivity in a mouse model of IgE-mediated passive cutaneous anaphylaxis and (2) Identify mast cell-regulated pathways at the intersection of allergic and chronic vulvar pain pathologies in vulvar pain provoked by chronic labiar contact hypersensitivity. We will use thermal and mechanical pain measurements, semi-quantitative single/multiplexed PCR, immuno-fluorescent, confocal, and transmission electron microscopy, and protein assays (ELISA, western blot, flow cytometry). We build on groundwork laid in our previous NIH- supported work (R15 NS067536-01A; 2010-2013) on contributions of mast cells to acute, inflammatory pain. Preliminary findings indicate that acute allergic reactions mediated by different IgE antibodies against the same antigen can provoke different pain outcomes, and chronic allergic reactions can change the long-term pain sensitivity of affected tissue even after overt allergic inflammation has resolved. Mast cells and nerves reside in close proximity in many tissues and regulate each other through networked signals of neurotransmitters, cytokines and adhesion molecules. Identification of key mediators of nerve-mast cell interactions in allergy- associated pain will provide novel mechanistic insights applicable beyond any single allergy or pain disorder and lead to novel therapeutics and strategic interventions that enhance progress toward improved health and quality of life.